PROBLEMS IN BUS FIRE SAFETY – RECENT DEVELOPMENTS AND POSSIBLE SOLUTIONS

摘要

Not only the severe bus fire in 2008 near Hanover in Germany with 20 fatalities showed the fire danger for coaches1,2. Also two other similar fires in Germany in May 2011 and February 2012 showed the extremely hazardous situations a fire can cause in bus3,4. In both cases young and fit passengers (pupils) could only escape because they were able to destroy windows and escaped by jumping out of these windows. In one case they had to escape out of the windows of the upper deck and several were severe injured. These numerical and experimental investigations of bus fires in coaches and city buses performed by BAM are funded by the German Ministry of Transport, Building and Urban Development. Web and literature research showed that fires occur much more often than assumed. Most of the fires start in the engine compartment. However, often the whole bus is destroyed after a fire. One reason for the rapid fire development are the fire safety regulations for the bus materials which are on a much lower level than in the other transport sectors1,2,5,6,. A lot of materials from suppliers and of operating city buses were investigated experimentally. The results were compared with regulations in the train sector because trams and city buses, trains and coaches are working under similar operating conditions, e.g. for escape possibilities. These results were used to investigate bus fires also numerically to identify very hazardous scenarios by varying materials properties, geometries and air condition settings. Especially the newer bus seats showed a very low fire performance with high heat and smoke release rates. Surprisingly a city bus seat of an older bus (built in 1995) showed a better fire performance. It is assumed that the trend to cheaper and lightweight plastics is one reason that modern seats have worse fire performance. Large scale tests were performed on a city bus – smoke development, fire detection and suppression in the engine area. Several possible enhancements are discussed and recommendations are given to make buses more fire safe.